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/* Copyright (c) 2010, Paul Hsieh
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* * Neither my name, Paul Hsieh, nor the names of any other contributors to the
* code use may not be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stddef.h>
#include <stdint.h>
#undef get16bits
#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) || \
defined(_MSC_VER) || defined(__BORLANDC__) || defined(__TURBOC__)
#define get16bits(d) (*((const uint16_t *)(d)))
#endif
#if !defined(get16bits)
#define get16bits(d) \
((((uint32_t)(((const uint8_t *)(d))[1])) << 8) + \
(uint32_t)(((const uint8_t *)(d))[0]))
#endif
uint32_t SuperFastHash(const char *data, int len, uint32_t hash)
{
uint32_t tmp;
int rem;
if (len <= 0 || data == NULL)
return 0;
rem = len & 3;
len >>= 2;
/* Main loop */
for (; len > 0; len--) {
hash += get16bits(data);
tmp = (get16bits(data + 2) << 11) ^ hash;
hash = (hash << 16) ^ tmp;
data += 2 * sizeof(uint16_t);
hash += hash >> 11;
}
/* Handle end cases */
switch (rem) {
case 3:
hash += get16bits(data);
hash ^= hash << 16;
hash ^= ((signed char)data[sizeof(uint16_t)]) << 18;
hash += hash >> 11;
break;
case 2:
hash += get16bits(data);
hash ^= hash << 11;
hash += hash >> 17;
break;
case 1:
hash += (signed char)*data;
hash ^= hash << 10;
hash += hash >> 1;
}
/* Force "avalanching" of final 127 bits */
hash ^= hash << 3;
hash += hash >> 5;
hash ^= hash << 4;
hash += hash >> 17;
hash ^= hash << 25;
hash += hash >> 6;
return hash;
}
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